The present invention relates to the purification and concentration of synthetically manufactured biological molecules. More particularly, it relates to the purification and concentration of synthetically manufactured biological molecules, such as oligonucleotides, synthetic DNA and synthetic RNA, by ultrafiltration.
Synthetic biological molecules, such as oligonucleotides, synthetic DNA and synthetic RNA are being investigated as therapeutic agents. These molecules would be used in lieu of natural or recombinant molecules. There are a number of reasons for doing so. Some molecules just don't exist in nature or for some reason can't be replicated yet using recombinant technologies. Synthetic synthesis can overcome this limitation. Often, there are variants of eth same molecule. Synthetics allow one to custom tailor the molecule to its desired form. Lastly, synthetics and their manufacture are often less expense to manufacture and often avoid the issues of handling biohazards.
These molecules are typically formed by synthetic chemical precursors and are assembled on various solid substrates within synthesizers.
After formation, they need to be purified and in many instances concentrated, either for further processing or formulation.
The molecules generally are cleared from their solid support and then subjected to a purification step such as ultrafiltration or chromatographic capture to remove impurities.
The desired molecules are relatively small, typically having a molecular weight from about 0.5 to about 5 Kilo Daltons (KD).
As such, they are difficult to purify and concentrate by ultrafiltration as they are often about the same size as the membrane pore used to retain them. This results in relatively low yields of product being obtained Additionally, the membranes, having such small pore sizes, suffer from low fluxes and processing times can be measured in hours. This drives up the cost of the process as well as placing an undue burden on the membranes and the system components.
Due to this limitation, ultrafiltration is not widely accepted for this application and one uses chromatography, precipitation or distillation techniques to purify and concentrate these molecules.
These processes have their own disadvantages. They are biotech-based and most times, especially process scale chromatography, are more expensive than ultrafiltration. The precipitation often introduces an additional chemical that needs to be removed. Distillation may adversely affect the molecules especially any that are heat sensitive.
The present invention provides the means for enabling ultrafiltration in this application.